1. Technical Field
The present invention relates to an optical device and an image display apparatus.
2. Related Art
In recent years, as an image display apparatus such as a projector, there has been known an apparatus that displays an image including multiple pixels by enlarging the image through an optical system such as a lens.
Such an image display apparatus generally uses a method of increasing the pixel density by shrinking each pixel and increasing the number of pixels so as to improve resolution. However, since it is difficult to configure smaller pixels, the method has a problem in that, for example, the yield is decreased, or the manufacturing cost rises.
An image display apparatus is disclosed in JP-A-2011-158589 with consideration of such a problem. The image display apparatus is provided with an optical device, a so-called image shifting device (image shifter), that shifts the position of capture of an image generated by image forming elements. Accordingly, it is possible to increase the resolution of a displayed image without increasing the pixel density.
The optical device disclosed in JP-A-2011-158589 includes a glass plate that changes the optical path of light, a holding member that holds the glass plate, and two flat springs that support the holding member. The optical path of light transmitted through the glass plate can be shifted by oscillating the glass plate that is fixed to the holding member around the two flat springs as the axis of oscillation. Accordingly, it is possible to shift the position of capture of a generated image by shifting the optical path.
In the optical device disclosed in JP-A-2011-158589, however, since it is hard to form the glass plate at predetermined dimensions, it is difficult to cause the entire side face of the glass plate to about evenly on the holding member. Thus, the two flat springs have different rigidities, and the glass plate does not oscillate uniformly. Accordingly, the stability of the optical path is decreased, and this poses a problem in that the quality of a displayed image is decreased.